1. Field of the Invention
This invention relates generally to semiconductor electro-optic microstructures, and more particularly, to a quantum well arrangement wherein an air, acrylic resin, vacuum, or other barrier is utilized to achieve high reflectivity.
2. Description of the Related Art
Conventional multi-layer dielectric mirrors are formed of plural layers of materials, each such material being characterized by a respective index of refraction n. In mirrors which are formed of two materials of refractive indices n.sub.1 and n.sub.2, with thicknesses of d.sub.1 and d.sub.2, the reflectivity will, to a significant extent, scale with the difference in the refractive indices, i.e., .DELTA.n=n.sub.1 -n.sub.2.
A significant problem with making reflectivity mirrors from III-V semiconductors is that the difference between the respective indices of refraction is not large, and accordingly, a large number of pairs of layers is required to achieve a desired reflectivity. The problem is particularly difficult for DBR mirrors for long wavelengths, .lambda.. For example, in order to achieve a mirror with maximum R.about.0.999 in the InGaAs/InP system, some 49 pairs of layers are required. This stems from the fact that in a typical III-V system, n.sub.1 =3.17 and n.sub.2 =3.5.
It is, therefore, an object of this invention to provide an electro-optic microstructure wherein a plurality of quantum well structures are confined on both sides by a barrier having a highly contrasting index of refraction.
It is another object of this invention to provide a semiconductor electro-optic microstructure which is characterized by high reflectivity without the need for many layer pairs.
It is also an object of this invention to provide a Fabry-Perot optical resonator cavity having a linear dimension on the order of the spontaneous emission wavelength of the active medium.
It is a further object of this invention to provide a laser arrangement having a low emission threshold.
It is additionally an object of this invention to provide a semiconductor electro-optic microstructure which is characterized by high index of refraction contrast ratio and which can be fabricated with conventional fabrication techniques.
It is yet a further object of this invention to provide a Bragg mirror arrangement which achieves high reflectivity using very few layer pairs.
It is also another object of this invention to provide a tunable Bragg mirror arrangement.